https://dreamhack.io/wargame/challenges/17

풀이

계산식

K[i] = (i ^ ans[i]) + 2i
ans[i]^i = K[i] - 2i
ans[i] = (K[i]-2i)^i

exploit

답 출력해주는 스크립트

k = [0x49, 0x60, 0x67, 0x74, 0x63, 0x67, 0x42, 0x66, 0x80, 0x78, 0x69, 0x69, 0x7B, 0x99, 0x6D, 0x88, 0x68, 0x94, 0x9F,
     0x8D, 0x4D, 0xA5, 0x9D, 0x45, ]

ans = []
for i in range(len(k)):
    v = (k[i] - 2 * i) ^ i
    ans.append(chr(v))

print(''.join(ans))